backfire after plug change?

Jaswir

Member
Mar 31, 2005
578
0
18
Orlando, FL
just changed my plugs... i went with NGK v power plugs.. now after the plug change with WOT or 3/4 of throttle pushed it backfires threw the exhaust! not loud just a bunch of lil ones... i check out plug wires everything is pluged in correct and is tight.. gaped them at 45 and before i had auto light 25s at 54.. think maybe its just a bad plug from the factory? also went to back of car and looked under it and my car has flows dumped so my eyes started to water because of unburnt fuel! so i think i might go back to auto 25s if i cant get to run right... any suggestions?
 
Jaswir said:
i know for a fact i didnt cross the wires, i did one at a time and as soon as i changed one i put the wire back on it!
OK. If you are sure you didn't cross any then I would try to put the old plugs back in to rule out the new plugs being the issue. If not you may have damaged the end of one of the wires.
 
You can run a CBT to see if the puter can decipher what cylinder is missing (might be fun to do, for fun's sake).

I agree with Tim et al - go with Motorcraft or Autolite (I use the latter) copper plugs.

Good luck.
 
ok today i bought auto 25's what i always ran on my car and changed them now it runs WORSE! Now back fires loud as hell going above 3 to 4 thousand rpms! so i think it might be a plug wire maybe damaged one putting it back on? so i think im gonna change the plug wires tomorrow.. i don't know whats up with it
 
If you have a timing light, you can toss it on each wire and hit the trigger. Look for an intermittant light pulsing.

Even just separating each wire from one another can help with cross firing.

Pulling codes and the CBT still could be helpful.

Good luck.
 
ok found the problem, it was the NGK plugs i put in... maybe they gave me the wrong ones? ok after i put in my auto lite 25s i put timing back to where it was.. because i played with it when i put the NGK plugs... what happen was i put spout connector in my pocket and forgot about it... so that was it i didnt put the spount back on after changing the timing... i guess i was in too much of a hurry... now im gonna change my balancer tomorrow! :)
 
definetly had a buddy do that after he installed his nitrous kit. set the timing and forgot to put the plug back in. took it down the road, sprayed it and POP! blew a head gasket. we searched for quite some time to figure out what happened until i asked him if he ever put the spout back in after we set the timing since he was the one that took it out. well it was in his pocket. anyways, glad to hear its running better